The next layer is the third layer of the U.S. reference model, the network layer.
The network layer provides the means of transferring variable length network packets from a source to
a destination host via one or more networks.
In other words, the network layer is responsible for packet forwarding, including routing through
intermediate routers.
Within the service learing semantics of the U.S. network architecture, the network layer responds to
the service requests for the transport layer and issues service requests do the data link layer.
So here are the functions of the network layer.
Connection, less communication.
For example, IP is connection was in that data packet can travel from a center to a recipient without
the recipient having to send an acknowledgement.
Connection oriented protocols exist at other higher levels of the U.S. model.
Host addressing.
Every host in the network must have a unique address that determines where it is on the Internet, addresses
are known as IP addresses, right?
Message forwarding, since many networks are partitioned into sub networks and then connect to other
networks for a wide area, communications networks use specialized hosts called gateways or routers
to forward packets between networks.